An imaging catheter which is constructed to be inserted into a guiding catheter having a small outer diameter, such as 5 French, such that a standard guidewire and imaging catheter are simultaneously translatable through a lumen of the guiding catheter. The imaging catheter includes an elongated tubular member and a cover tube made from materials which allow the outer diameter of the imaging catheter to be reduced sufficiently to fit within the small guiding catheter without sacrificing imaging quality.